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GATE 2019 ME (ME1) – Question 18

Thermodynamics · Zeroth, first and second laws, work, heat and energy changes · 1 mark · Multiple choice

During a non-flow thermodynamic process executed by a perfect gas, heat interaction equals work interaction. Which process gives this equality?

  1. Isentropic
  2. Polytropic
  3. Isothermal
  4. Adiabatic

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Show answer and explanation

Correct answer: (C) Isothermal

Explanation

The first law gives Q-W=ΔU. Equality Q=W therefore requires ΔU=0. For a perfect gas internal energy depends only on temperature, so temperature is unchanged: the process is **isothermal, C**. Adiabatic alone means Q=0 and need not give zero work.